This is something you have to be born with, I think.
It is the ability to play three, four or five notes and be instantly recognizable. And it doesn't matter whether the player who posseses this rare gift is historically famous or a complete unknown.
For the rarest of this breed, one can even define eras by their influence on generations of guitarists, for example pre-Van Halen and post-Van Halen, or pre-Charlie Christian and post-Charlie Christian.
For most of us music mortals, a style is created by fusing several influences. And if one has listened widely, those influences can still be clearly picked out.
The unique innovator, on the other hand, has taken the amalgam of his influences and distilled them into a recognizable signature sound and style.
And then there is the true innovator.
The true innovator takes what has come before him, throws most of it out the window and re-invents the instrument. While sometimes influencing generations of players. You'll usually know who they are after just four or five notes.
This is a partial list of who I feel are the true innovators of the guitar world, past and present:
George Van Eps
Stevie Ray Vaughan
Eddie Van Halen